Mycoplasmas are placed in a separate class, Mollicutes, which removes them from bacteria. Their main characteristics are lack of a cellular wall and inability to synthesize the peptidoglycan polymer. The lack of a cell wall accounts for the pleomorphism, osmotic sensitivity, sensitivity to antibiotics that inhibit pep tidoglycan polymerization and synthesis, susceptibility to lysis by alcohol and detergents, and the ability to grow on agar gel. At present, three families are placed in the class Mollicutes: Mycotaceae, Acholetaceae, and Spiroplasmataceae. The first pathogenic mycoplasmas were...